Placebo effect of using "own" pillow as a comparator in an experimental study

Objectives To establish whether use of a specific type of "own" pillow influences responses to experimental pillows.Methods Eighty-one subjects participated in two concurrent experimental studies [Studies 2 and 3, Figure 1, Paper 1]. Both studies compared subjects' responses to five experimental pillows [polyester, foam regular and contour, feather, and latex] with subjects' "own" pillow. Study 2 collected prospective information on sleep disruption, waking cervico-thoracic symptoms, sleep quality, and pillow comfort over a week on each of the trial pillows, and Study 3 explored differences in dimensions and cervical posture in side lying on the same trial pillows. The biggest differences between depths of "own" pillow and similar trial pillow types were for foam and feather pillows, followed by latex pillows. Correlations between depth differences and waking symptoms on "own" pillow were not significant, suggesting that pillow compression [with age] was not a predictor of waking symptoms. Usual foam contour and latex pillow users were strongly negatively sensitized to the effects of any other trial pillow, in that they preferred the trial version of their "own" pillow type. They most disliked the feather pillow. Feather pillow users, however, were strongly positively sensitized to the effect of all other trial pillows, preferring them over their "own" pillow.Conclusions There is a clear sensitization/placebo effect most relevant to latex, foam contour, and feather pillows.